In a supercritical vapor compression cooling cycle using carbon dioxide or the like as a refrigerant, in order to increase a cooling capacity or prevent liquid compression by a compressor, use of an auxiliary heat exchanger for heat exchanging a high pressure refrigerant passing through a condenser with a low pressure refrigerant introduced into a compressor has been provided.
If such an auxiliary heat exchanger is further installed to a cooling system, problems, such as difficulty in an assembling work due to complexity of tubing of the cooling system, enlargement of the cooling system, and poor loadability, occur.
In order to solve the problems, an accumulator heat exchanger (AHX), in which an auxiliary heat exchanger is installed inside an accumulator, has been proposed.
Most of accumulator heat exchangers conventionally proposed have the configuration that a tube in which a low pressure refrigerant flows and a tube in which a high pressure refrigerant flows are in contact with each other and a plurality of plate-shaped fins are attached to an outer surface of each tube to increase a heat exchange area.
However, the accumulator heat exchanger having this configuration has low heat exchange efficiency since the heat exchange occurs only through the contact area between the refrigerant tubes.